1. Field of the Invention (Technical Field)
The present invention relates to heart compression and assist and arrhythmia control devices. More particularly the invention relates to a multi-soft fingered, resilient electrical heart compression apparatus which can be implanted external to the patient's heart for compressing a heart ventricle robotically and intelligently, which contains control means such as bradycardic (pacing) and tachyarrhythmic (cardioverting/defibrillating) to facilitate the device operation in synchronism with left ventricular contraction. The apparatus is also preferably capable of transcutaneous recharging of the implanted batteries, or can be powered by a pair of transcutaneous conducting wires by an electronic battery pack system worn around a user's waist.
2. Background Art
There presently exists no implantable heart compression device to help patients suffering from congestive heart failure (CHF), a progressive disease often precipitated by acute myocardial infarction. All artificial heart or left ventricular assist devices have either not worked in the past or are just temporary solutions for patients needing a donor heart for transplant. Existing devices generally feature blood flow pathways made from non-biological materials that often damage blood cells and blood proteins and produce clots, thereby presenting a generic risk thromboembolism in the circulatory system. In fact, blood clots cause most of the deaths reported after implantation of an artificial heart or assist device. The majority of these patients have a normal right ventricle; however, most have a left ventricle that has been damaged in specific regions. Therefore, there is a need for a heart compression device designed to assist the weak muscles of a failing heart that augments the heart's pumping power. This device could also incorporate pacemaker and implantable cardioverter/defibrillator technology for treating patients who also suffer from such electrical dysfunctions as bradycardia or tachyarrhythmias. Current Left Ventricular Assist Device (LVAD) devices are heavy and generally have to be attached to a cart to be dragged around by the patient. In addition, they lack a satisfactory implantable energy source, requiring patients to be constantly tethered to an external power source. Previous attempts to provide ventricular assistance have ranged from artificial hearts (e.g., the Jarvik-7), to devices which directly pump the blood, via an artificial pathway inserted through the ventricular wall to devices which exert pressure on the outside of the heart. Historically, heart-compression devices involve some form of flexible bladder within a support structure such that expansion of the bladder presses on the ventricle and facilitates expulsion of blood. These types of devices are disclosed in U.S. Pat. No. 3,587,567 to Schiff; U.S. Pat No. 3,371,662 to Heid, et al.; U.S. Pat No. 4,048,990 to Goetz; and U.S. Pat No. 4,192,293 to Asrican. U.S. Pat. No. 4,506,658 to Casile discloses a truncated conical structure of sac-lined rigid panels separated by contractible and expandable sections. Another type of cardiac assist system is designed to compress all or part of the heart by alternately tightening and releasing a circumferential compression band. For example, U.S. Pat. No. 4,304,225 to Freeman teaches the use of a flexible strap which is fixed to a contoured plastic block and which would pass across the back of the heart. In response to electrical pulses, a motor assembly alternately reels in and releases the flexible strap, thereby forcing fluid from the organ. This prior art device is ineffective because a pressure of between 20 and 70 mm Hg in the volume under the strap pumps blood from the right ventricle but not the left, since 70 mm Hg or more is required for blood to exit the left ventricle into the aorta. Freeman also discloses the use of a tubular compression sleeve that substantially encircles the heart and which comprises a series of interconnected expandable elliptical chambers. In use, a liquid solution is pumped into the sleeve from a supply chamber, causing the elliptical chambers to expand radially inward to compress the heart in its systolic phase. The solution then is released from the sleeve back to a supply chamber, permitting the heart to expand in its diastolic phase. These bladder-type devices can lead to a buildup of blood in the lungs, producing pulmonary complications. U.S. Pat. No. 4,583,523 to Kleinke and Freeman illustrates another prior art heart assist mechanism. This device compresses the aorta, not the left ventricle, and it compresses during the diastolic phase of cardiac contraction instead of the systolic phase. There is no means to monitor the adequacy of left ventricular stroke volume.
U.S. Pat. No. 4,925,443 to Marlin S. Heilman and Steve A. Kolenik, discloses an implantable ventricular assist device which includes, (1) one or more movable compression assemblies for engaging a ventricle of the heart; (2) an operating mechanism for cyclically actuating the movable compression assemblies and thereby alternately ejecting blood from the ventricle and permitting the ventricle to refill; (3) a sensing means to detect adequacy of ventricular stroke volume and/or pressure; (4) a control mechanism to assure adequate ventricular stroke volume by regulating the compressive force of the compression assemblies, and also to control pacemaker, cardioverter/defibrillator, and recorder subsystems; and (5) an electrical power source.
To prevent the edges of the compression assembly pressure plates from creating pressure points which might cause possible damage to the heart, a related continuation-in-part patent, U.S. Pat. No. 5,098,369, to Marlin S. Heilman, et al., discloses replacing the contact pad of each compression assembly with a gel-filled contact pad of special construction that compresses the heart ventricle more uniformly without damaging the ventricle. Another related patent, U.S. Pat. No. 5,098,369, to Heilman, et. al., discusses a ventricular assist device for a heart which includes a compression band-stay-pad assembly for encircling substantially the entire heart perimeter and comprising an elongated band member or chain disposed in a sealed protective structure filled with a lubricating medium.
Yet another related patent, U.S. Pat. No. 5,558,617, to Heilman, et. al, discusses a ventricular assist device for a heart including a compression band-stay-pad assembly for encircling substantially the heart perimeter and comprising an elongated band member or chain disposed in a sealed protective structure filled with a lubricating medium. The band member is fixed at one end and wound upon, or unwound from, a rotatable spool by a drive motor through a speed reducer.
Other previous attempts to provide ventricular assistance have ranged from artificial hearts (e.g., the Jarvik-7), to devices which directly pump the blood via an artificial pathway inserted through the ventricular wall, to devices which exert pressure on the outside of the heart. Most frequently, these latter pressure-exerting devices involve some form of flexible bladder within a support structure such that expansion of the bladder presses on the ventricle and facilitates expulsion of blood. These types of devices are disclosed in U.S. Pat. No. 3,233,607 to Bolie; U.S. Pat No. 3,279,464 to Kline; U.S. Pat No. 3,587,567 to Schiff; U.S. Pat No. 3,371,662 to Heid, et al.; U.S. Pat No. 4,048,990 to Goetz; U.S. Pat No. 4,192,293 to Asrican; U.S. Pat No. 3,455,298 to Anstadt; U.S. Pat No. 4,690,134 to Snyder; U.S. Pat No. 5,169,381 to Snyder; U.S. Pat No. 5,256,132 to Snyder; U.S. Pat No. 4,731,076 to Noon et al.; and U.S. Pat No. 4,957,477 to Lundbäck. U.S. Pat. No. 4,506,658 to Casile discloses a truncated conical structure of sac-lined rigid panels separated by contractible and expandable sections. U.S. Pat. No. 4,621,617 to Sharma shows another similar device which is electromagnetically controlled and comprises a pair of hinged compression members. Further, U.S. Pat. No. 4,536,893 to Parravicini teaches using two segmented sacs, selectively fed by a pumping fluid to compress the right and left ventricles separately. In general, bladder systems have various shortcomings. These include the possibility of catastrophic bladder fluid leakage (as a result of the fluid pressures involved), a propensity for damaging the heart surface due to poor fixation and/or rubbing of the bladder against the heart's surface, and the unnatural convex form presented to the heart's surface during systolic bladder expansion. U.S. Pat. No. 4,583,523 to Kleinke and Freeman illustrates a heart assist mechanism that compresses the aorta, rather than a ventricle, and it compresses during the diastolic phase of cardiac contraction instead of the systolic phase.
Other prior art references of relevance to the present invention are: U.S. Pat. No. 5,250,167 to Adolf, et al., and U.S. Pat No. 5,389,222 to Shahinpoor in connection with electrically controllable polymeric actuators; Y. Wakisaka, et al., “Application of Hydrogen Absorbing Alloys to Medical and Rehabilitation Equipment”, IEEE Trans. on Rehabilitation Engineering, Vol. 5, No. 2, pp.148–157 (1997); M. Shahinpoor, “Ionic Polymer Metal Composition as Biomimetic Sensors and Actuators”, in Polymer Sensors and Actuators, edited by Y. Osada and D. DeRossii, Springer-Verlag Publishing, Springer (1999); and M. Shahinpoor, Y. Bar-Cohen, J. O. Simpson, J. Smith, “Ionic Polymer Metal Composites (IPMC's) as Biomimetic Sensors, Actuators and Artificial Muscles—a Review”, J. Smart Mater Structures, Vol. 7, pp 15–30 (1998).